eson

eson is a work in progress tool to extract a normalized schema from a denormalized relational schema. The hope is that it can be useful for understanding and managing schemas of NoSQL applications.

Input format

Example input files are available in the examples directory. Input files to eson are split into four different sections. The first specifies the denormalized input relations in the following format:

users(*user_id, first_name, last_name)

Fields marked with a * compose the primary key of that relation. The second section specifies functional dependencies for each table. The table name is given first, followed by the left and right-hand sides of the dependency.

users user_id -> first_name, last_name

Inclusion dependencies are specified in a similar manner as in the examples below:

employees user_id <= users user_id
users user_id <= employees user_id

There are two shortcuts which can be used in this section. Firstly, if the inclusion dependency applies in both directions, then == can be used instead of separately specifying two dependencies. Second, if the fields on the right-hand side are the same as those on the left, ... can be used to replace the fields on the right. Employing both of these shortcuts, the two dependencies above can be written as:

employees user_id == users ...

The final section is optional and specifies statistics on tables and columns when using a heuristics-based approach for ordering functional dependencies (the --use-stats option). Statistics for a relation simply list the total number of entries in the relation. Statistics for a column list the number of unique values as well as the maximum length.

users 1000
users user_id 1000 1